C8/2002R Hazardous situation in transfer of broken-down commuter train and derailing of the train at Oulunkylä on 2 September, 2002
On Monday 2nd September 2002 at 7.29 hrs, P-train no. 9039 left Helsinki for Hiekkaharju. The northwards travelling train first stopped at Pasila and then just before its next stop at Käpylä, the automatic train control operated a braking of the train because of a too low pressure in the main air tank. The train stopped and the engine driver went to look for the leak. He detected the leak and managed to stop it by closing air valves. After an about 15 minute interruption, the journey continued to Käpylä and further to Oulunkylä where the passengers and the train crew left the train, as instructed by the remote-control operator. The intention was to take the trainset out of service for maintenance measures.
From Oulunkylä platform the remote-control operator directed the train northward to the west track behind the main signal. The driver moved over to the other end of the train so as to continue southward to Ilmala Depot. The driver contacted the traffic control room and received the following instructions: ”As displayed by signal aspects, in shunting mode to Ilmala”. But the signal mast failing to have a shunting sign, the driver thought that the ”Stop” signal aspect does not apply to shunting movements, and he could set out.
The driver continued southward at a maximum speed of 44 km/h, and on the turnout, the train started travelling toward the adjacent track where the next turnout position pointed straight forward to serve an express train heading southward. The commuter train trailed the turnout and derailed. The derailed train travelled over a distance of about 150 m. The driver of the express train approaching from the north managed to stop the train at a signal about 400 m from the point of the derailment. Also the other trains running in the vicinity stopped as required by the signal aspects, and hence no imminent danger of collision arose.
The derailment caused no personal injury, but the rolling stock suffered damage and three turnouts on the track were broken. The damage generated by the derailment amounted to about € 150 000.
The hazardous situation was caused by the engine driver having misinterpreted the train operator’s instructions. The main signal mast had no shunting work sign, and therefore the driver thought that the signal does not apply to shunting movements. However as specified in the relevant regulations, signal aspects displayed also concern shunting work. It is to be noted that the breaking down of the train on a Monday morning on a busy line strained the traffic control operators and the engine driver so as to generate an exceptionally risky situation.
To prevent such accidents the Accident Investigation Board of Finland recommends modifications to be adopted in the shunting-work sign system and the shunting work practices to be developed. The Board also recommends that the implementation of the automatic train control system be extended in shunting operations, as well, by carrying out technical improvements and issuing revised instructions.